Herbert h



H. H. DOW.

PROCESS 0F EXTRACTING BROMINE FROM BRINE.

APPLICATION FILED APR. 24, 1916. RENEWED APR. I7. ISIS. 1,823,173.

.Hexagzr H. Dow

, such a. brine, with the incidental extraction l UNITED STATES PATENT oEEicE.

HERBERT H. DOW, OF MIDLAND; MICHIGAN, ASSIGNOR T0 THE DOW/CHEMICAL COMPANY, OF MIDLAND, MICHIGAN, A CORPORATION 0F MICHIGAN.

PROCESS 0F EXTRACTING- BROMIN FROM BRIN'E.

Specification of Letters Patent.

Patented Nov. 25, 1919.

Application led April 24, 1916, Serial No. 93,313. Renewed April 17, 1919. Serial No. 290,901.

To all whoml 'it may concern:

Be it known that I, HERBERT H. Dow, a citizen of the United States, and a resident vof Midland, county of Midland, State of Michigan, have invented a new and usefulv that principle, so as to distinguish it from v other inventions. A

The present improved process and apparatus for carrying on the same, relating as indicated to the extraction of bromin from brine, have regardmore' particularly to cer-` tain improvements in. the general process described and claimed in U. S.' Letters 4Patent No. 714,160, Aissued to me November 25, 1902. In dealing with natural brines, such as those herein involved, it must be remembered that there is only'atrace of bromin present in the form of bromid, and that. to take all of this out in practice, without at the same time taking out a large amount of `chlorin, which is present in the form f' chlorid in very much larger quantities, is a matter'of no small diiiiculty. The object of the present invention is to providefor the systematic removal of all the bromin from carrying out the invention, such disclosed i mode, however, constituting but one of various ways in which the principle of the invention may be used.

In said annexed drawing ,the single ligure there appearing represents diagrammatically a form of apparatus suitable for' use in carrying out the present improved process.

The aforesaid apparatus, as well as the process exemplified in its operation, in reality more closely resemble the apparatus and process forming the subject-matter of U. S.

' in the main system that the patent to Schaefer, for methods of extracting bromin, dated June 27, 1916, No.

1,188,838, than the original Patent No.- r714,160 referred to above. By means, however, of thev further changes herein made in such original apparatus, I am enabled to ac.-

complish the desirable result, of systematically overeoxidizing the brine without the accumulation of an excess of chlorin 'in the tioned, on the contrary, the excess'of free chlorin used in preliminarily oxidizing the fresh brine depletes the latter of bromid. more and more until the original under-- oxidation step becomes in reality an over' oxidation, and so much chlorin accumulates are unable to eliminate it.

The present apparatus, as in the lcase of.

puriliers therein y such prior patents com'prises a main s stem with a brme reservoir A from whic the other parts of such systemare supplied, and

'the auxiliary system likewise has a brine resp ervoir B from which the parts of suchsystem are supplied, as also the reservoir of the main system.

Referring, rst of all, to what has beenV I -styled the main :system of the apparatus, the

brine for the reservoir A is preliminarily treated in a tower B3, which constitutes in effect part of the auxiliary system. In other words, the brine from the tank B, constitilting the primary source of supply, as it passes'down through such tower, comes into contact with an ascending stream of air carrying free bromin and some chlorin, so

that such brine is enrichedby bromin, and v any ferrous salts, o r like impurities, are oxidized before the first oxidation step proper.

The brine from the reservoir A is {irst conducted to an oxidizer A1, where oxidation may be accomplished in any approved fashion, as by one of the various means explained in U. S. Letters Patent re No, 11,232. Thence the brine flows into a blowout tower A2 of familiar construction. The oxidation step carried on inthe aforesaid oxidizer is regulated so as to under-oxidize the brine, that is, free less than the total content of bromin. Accordingly, the gas recovered from the blowout tower will be fairly free -from chlorin, especially as the air therein used is that which has been preliminarily passed through tower B3.

F rom the blowout tower A2, the residual brine is conducted to a second oxidizer B1, forming part of the auxiliary system, where its further treatment will be presently explained.

The air carrying the 'bromin blown out of tower A2 is next passed through a brominfed purifier A3, of familiar construction, which serves to eliminate any traces of chlorin, and thence passes over into an absorbing tower A5, where a reducing agent such as iron, or other material capable of absorbing the bromin, is utilized in the formation of the final product, which will be ferrie broinid in case such iron is used.

The oxidation step in the auxiliary system is carried much further than the rst described oxidation step in the main system, so as not only to free all the bromin contained in the lbrine therein being treated, but more or less chlorin in addition thereto. The b Aine, with its content of these gases in solution, then passes through a blowout tower B2 to waste, the gases blown out being conducted to a purifying tower B4, preferably bromid-fed, although a reducing agent, that preferentially reacts with chlorin, may be employed therein, this tower ybeing designed to remove substantially all of the chlorin produced by the over-oxidation in the preceding oxidation step. The air with its bromin content, however, is carried on to tower B3, where the brine is treated preliminarily to such first or under-oxidation l step, as has already been described.

The present process not only presents all of the advantages over that of Patent No. 714,160 which the Schaefer process attains, but in addition, by the interposition of the purifying step following the over-oxidation of the brine in the auxiliary system, such present process practicallyeliininates chlorin from the remaining steps of the process, and

in particular prevents any accumulation of this element, which otherwise would prevent, in time, the operation of the process at all. As a result of the foregoing, the gas blown out of tower A2 in the main system includes practically nothing ibut bromin, so that a single purification step suffices, and this stage of the operation is correspondingly shortened. Moreover, it is of course,

Vunnecessary, with the foregoing arrangement, to accurately gage the amount of the overoxidation, as has been in practice necessary heretofore in order to avoid the accumulation of excess chlorin, so that the present process really provides, for the first time, for the practical use of an over-oxidizing step in a system of this sort.

In other words, the sum of the two oxidation steps, in practice, has heretofore had to be actually less than the content of bromin and reducing agents in the brine, otherwise chlorin was bound to' occur in increasing quantities first in the secondary system and then there will not vbe sufficient bromin enrichment of the brine fed to the primary system to prevent ove -oxidation in this system, so that as a result chlorin will develop in increasing amounts in this system also; whereas, by the present process, the total oxidation may be excessive and yet the net result is automatically balanced 'to e ual such bromin reducing agent content, t us insuring thorough extraction of the bromin, and, at the same time, iving an unusually pure product, uncontaminated with clilorid.

Other modes of applying the principle of my invention may |be employed instead of the one explained, change being made as regards the process herein disclosed, provided the step or steps stated by any one of the following claims or the equivalent of such stated step or steps be employed.

I therefore particularly point out and distinctly claim as mv invention 1. The process of extracting bromin from bromid-oontaining brine which consists in systematically over-oxidizing such brine and `reducing the products of such oxidation at one stage in the process so that the net result of such oxidation is substantially equal to the bromin content.

2. The process of extracting bromin from brine containing bromid, which consists in systematically over-oxidizing such brine whereby chlorin as well as bromin is freed, and then eliminating such chlorin b the use of bromid so that the net result o such oxidation is substantially equal to the bromin content.

3. In a process of extracting bromin from bromid-containing brine, the steps which consist in oxidizing such brine short of its bromin content; thereupon oxidizing such brine in excess of its bromin content; blowing out the bromin and chlorin liberated in such overoxidation step; substantially eliminating the chlorin from the gases thus blown out; and blowing out the bromin liberated in such under-oxidation step with the gas from the last-named step.

4. In a process of extracting bromin from bromid-containing brine, the steps which consist in oxidizin such brine short of its bromin content; tereupon oxidizing such brine in excess of its bromin content; blowing out the bromin and chlorin liberated in such over-oxidation step; substantially eliminating the chlorin from the gases thus blown out; oxidizing the brine preliminarilv to such under-oxidation step by treating with the bromin-containing gas from the last-named step; and then blowing out the bromin liberated in such uiider-oxidation step.

5. In a process of extracting bromin from bromid-containing brine, the steps which consist in oxidizing such brine short of its bromin content; thereupon oxidizing such brine in excess of its bromin content; blowing out the bromin and chlorin liberated in such over-oxidation step; substantially eliminating the chloriii from the gases thus blown out by purifying the latter with a material preferentially reacting with such Chlorin; and blowing out the bromin liberated iii such under-oxidation step with the gas from the last-named step.

6. In a process of extracting bromin from broinid-containing brine` the steps which consist in oxidizing such brine short of its bromin content; thereupon oxidizing such brine iii excess of its bromin content; blowing out the bromin and chlorin` liberated in such over-oxidation step; substantially eliniinating the chloriii from the gases thus blown out by purifying the latter with a bromid; oxidizing the brine pi'elimiiiarily to such under-oxidation step by treating with the bromincontaining gas from the last-named step; and then blowing out lthe broinin liberated in such under-oxidation step with the residual gas.

7. In a process of extracting bromin from brine containing biornid, the steps which consist in passing a current of air through such brine after having been oxidized in excess of its bromin content; substantially eliminating the chlorin from the gases thus blown out; then passing such air through such brine in its original state to eti'ect its preliminary oxidation and increase its bromin content; finally passing lsuch air through the brine after it has been oxidized short of its bromin content. 8. In a process of extracting bromin from brine containing bromid, the steps which consist in oxidizing such brine short of its bromin content; then oxidizing it in excess of such content; passing a current of air in succession through such brine in its second and iirst stages of oxidation in the order named; and substantially eliminating the chlorinl from such air between such stages.

9. In a process of extracting'bromin from brine containing broiiiid, the steps which consist in preliminarily oxidizin such brine; next oxidizin it short of its Iiroinin content; then oxidizing it in excess of such content; passing a current of air in succession through such brine in its third, rst, and second stages of oxidation in the orden named; and substantially eliminating the chlorin from such air between such third and first stages.

10. In a process of extracting bromin from brine containing broniid, the ste s which consist in preliminarily oxidizing such brine; next oxidizing it short of its bromin content; then oxidizing it in excess of such content; passing a current of air in succession through such brine in its third, first,

and second stages of oxidation in the order named; and purifying such air between such third and first stages with a material preferentially reacting with chlorin, whereby the latter is substantially eliminated.

11. In a process of extracting bromin from brine containing broinid; the steps which consist in preliminarily oxidizing such brine; next oxidizing it short of its bromin content; then oxidizing it in excess of such content; passing a current of airi in succession through such brine in its third, first and second stages of oxidation in the order named; and purifying such air between such third and first stages with a bromid, whereby the chlorin in such air is substantially eliminated.

l2. In a process of extracting bromin from brine containing bromid, Athe lsteps which consist in preliminarily oxidizing such brine with purified bromin-laden air; next oxidizing it short of its bromin content with an oxidizin agent other than bromin; and then oxidizing it in excess of such content, likewise with an oxidizing agent other than bromin.

Signed by me this 14th day of April, 1916.

ARTHUR N.PATR1ARCHE, J No. F. GBERLIN. 

